Total internal reflection (TIR) prisms are used with digital micromirror devices (DMDs) in projection systems to convey illumination light to the DMD, convey DMD on-state light towards projection optics, and convey DMD off-state light away from projection optics, for example to a light dump. However, the TIR surface of the TIR prism generally reflects at least a portion of the DMD off-state light back towards the DMD which decreases in projected images contrast due to both light scattering and a tendency of the DMD to convert at least some of the back-reflected DMD off-state light into higher order components of the DMD on-state light due to diffraction effects of the DMDs. Use of anti-reflective coatings at the TIR surface are generally optimized for transmission of the DMD on-state light therethrough, which exacerbates the problem. While AR coatings optimized for transmission of off-state light have been used at the DMD window, this can also exacerbate the problem as it increases the transmission of back reflected DMD off-state light from the TIR surface to the DMD.